-
Notifications
You must be signed in to change notification settings - Fork 1k
/
reader.go
103 lines (88 loc) · 3.84 KB
/
reader.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build go1.17
// +build go1.17
package metric // import "go.opentelemetry.io/otel/sdk/metric"
import (
"context"
"fmt"
"go.opentelemetry.io/otel/sdk/metric/export"
)
// errDuplicateRegister is logged by a Reader when an attempt to registered it
// more than once occurs.
var errDuplicateRegister = fmt.Errorf("duplicate reader registration")
// ErrReaderNotRegistered is returned if Collect or Shutdown are called before
// the reader is registered with a MeterProvider.
var ErrReaderNotRegistered = fmt.Errorf("reader is not registered")
// ErrReaderShutdown is returned if Collect or Shutdown are called after a
// reader has been Shutdown once.
var ErrReaderShutdown = fmt.Errorf("reader is shutdown")
// Reader is the interface used between the SDK and an
// exporter. Control flow is bi-directional through the
// Reader, since the SDK initiates ForceFlush and Shutdown
// while the initiates collection. The Register() method here
// informs the Reader that it can begin reading, signaling the
// start of bi-directional control flow.
//
// Typically, push-based exporters that are periodic will
// implement PeroidicExporter themselves and construct a
// PeriodicReader to satisfy this interface.
//
// Pull-based exporters will typically implement Register
// themselves, since they read on demand.
type Reader interface {
// register registers a Reader with a MeterProvider.
// The producer argument allows the Reader to signal the sdk to collect
// and send aggregated metric measurements.
register(producer)
// Collect gathers and returns all metric data related to the Reader from
// the SDK. An error is returned if this is called after Shutdown.
Collect(context.Context) (export.Metrics, error)
// ForceFlush flushes all metric measurements held in an export pipeline.
//
// This deadline or cancellation of the passed context are honored. An appropriate
// error will be returned in these situations. There is no guaranteed that all
// telemetry be flushed or all resources have been released in these
// situations.
ForceFlush(context.Context) error
// Shutdown flushes all metric measurements held in an export pipeline and releases any
// held computational resources.
//
// This deadline or cancellation of the passed context are honored. An appropriate
// error will be returned in these situations. There is no guaranteed that all
// telemetry be flushed or all resources have been released in these
// situations.
//
// After Shutdown is called, calls to Collect will perform no operation and instead will return
// an error indicating the shutdown state.
Shutdown(context.Context) error
}
// producer produces metrics for a Reader.
type producer interface {
// produce returns aggregated metrics from a single collection.
//
// This method is safe to call concurrently.
produce(context.Context) (export.Metrics, error)
}
// produceHolder is used as an atomic.Value to wrap the non-concrete producer
// type.
type produceHolder struct {
produce func(context.Context) (export.Metrics, error)
}
// shutdownProducer produces an ErrReaderShutdown error always.
type shutdownProducer struct{}
// produce returns an ErrReaderShutdown error.
func (p shutdownProducer) produce(context.Context) (export.Metrics, error) {
return export.Metrics{}, ErrReaderShutdown
}